Electronic counter duration indicator



Aug. 16, 1949. o. T. FRANCIS ELECTRONIC COUNTER DURATION INDICATOR Filed Feb. 1, 1945 4 .5 7 7 z z 7 z z I 65% I Patented Aug. 16, 1949 UNITED iv STATES I PAT sp-m;-

ELECTRoNIoCOUNmEmDURN-HON ii INDICATOR l Oliver T. Francis, Renville; Minn; I Application February 1, 1945, sexism. avsissa 7 Claims. (01: 2351-92) This. invention relates. to electronic counters, andmore particularly to a means for counting the pulses produced at a predetermined frequency for adurationlto be determined. I

Various'impulse duration indicating devices are known. These devices usually take the. form. of means for changingthe chargeon a condenser at a..predetermined rate for the duration of the impulse and-indicating the charge remaining on the condenser. atthe endof said duration. The accuracy-of saiddevices. depends on theconstancy of sources of voltage, which sources comprise the .B and C batteries in vacuum tube duration-indicatingcircuits. Sources of-Bi battery are. usually obtained fromrectifying alternating current, and even with. the most advanced voltage regulator systems it is impossibleto obtain ,a constant B supply it, the alternating; current voltage varies over- Wide latitudes, Commercial alternating-current voltages vary as much:. as. ten percent, and withsmall plants, such as found aboard ship, the variation may be as much as forty percent. It is one-of the objects of this invention to provide an impulse duration indicating device whichshall be accurate-Tegardless-of;widevariations in -B and G? battery'voltages V Dueto: the. phenomenon. ofresonance it has been possible, to produce alternating. currents of very exact predetermined frequency. At. radio transmitting stations, for example, a variation of one: ten thousandth of the-frequency from that assigned. is inexcusable. It is one of the objects of this invention toiprovide pulses at a constant frequency for the duration of an impulse and to. count the number of pulses so produced as". an indication of said duration. I 7

Another object isto provide an accurate elec-- tronic' counter. which shall be substantially independent- .of- B and. 0 battery voltagewariations,

Due-to-the phenomenon of magnetic saturation the amount: of energythat can be stored in an iron core. inductance i-s limitedandis substantially independent of current flowing through; the inductance-T after the saturationvalue is reached. ltviszone of the obiectsof this-invention toprovide; 52,11 electronic counter which shall' total the energy storedv in'such an' i-nduc-tancea-number-oftimes to be counted.-

Another, object is vto provide a means for: passing-current throughtheprimary of a-transformerainumber. of times to be determined, and means: including the secondary- 0f; saidltrans-formenrfor indicating the total amount of; energy stored in the core ofsaidtransformer. I

Another object isto-provide. a. screen grid tube for. passing; a current. from. a. voltage source through an inductance a. number. of times, said tube having alsufficiently-high A. C. impedance .t'o limit..'said..current\ to. a? predetermined magnitude regardless of. variationsihyoltage. of.said source, and-me ans: for indicating thetotal energy. sto ed insaidinductancm f Another object is to provide means for. dis.- charging, the. storing means ,when. ithas reached amnedeterminedyoltage. and a. second. electronic counterfor indicating the. total number of. time said storing. means reaches...thatvoltage.

Another object'isstoprovide an auxiliary, means for. operating. said seeondlemctronic. counter,

whereby; the. total. number. indicated by. said secondtcounteri maybe. the total of; thenumber of timesthefirst counterreachessaid predetermined voltage plus the. amounts produced by, said; aux? mfiWrmBaIlSs 7 r The utilization-bf; aQfirst electronic counter for indicating the funits. anda second \for. the tens? has beentproposedi Ittis an obj cot-of. this inventionitmprovide sucha plurality of cascadeocon! nected counters, wherein.the tens counter may be; actuated by,- clearing,thev unit" counter and an auxiliary imeans for; operating the. tens. counter, .to add numbers with.a ten. component;

Anothenobjectis 5110. provide ameans .ror adding two successivea differentg duration; impulsesv and indicating the total durationrof said. two ime .ABOthGI'rQbj-QCI is @toprovide. .a means for adding asignaLhaving. a. unit. andaPten. component.

Another object is to provide a noyelmaveshaping-dev-ice for pulsesto be counted. 1

and other, obi ectswilLbecome-apmrent from theiollowing,claims,..description.and figures,- wherein: I

' Fig l, ..shows.an impulse duration. indicating device embodyin inyinvention,and, V

Fig. .2-.shows .a plurality, of impulses, for. apply.- ingftolmy. device, .3..is a. modification; of

Fig. v

Referring. to Eig. .1, vacuum tube 1 35. is. .of. the multiple.grid .type;..such.asalpentigrid.eonverter, Its... first. grid-isv connected, through; resistance. .34 to. one ,terminal loft an; alternating. current. gen.- erator. 31.. lts fourth. grid is connected. to. the other terminal .of generator 3]. through resistance. 335-.- Its=cathodeisconnected.tothe mi p l n resistance. which; latter. 1 resistance; isv across. generator 31 llhefloutputhcircuit. of :tube 35 can be traced iromthepositiveterminalof battery I, th olishtresistancefl; ,anode to..cathode...o .tube

35, to the ground 2 terminal of battery The anode of tube 35 is connected through condenser 31 and resistance 38 to the control grid of a high A. C. impedance screen grid vacuum tube 3. Resistance 39 is connected as a grid leak for this control grid. The screen grid of tube 3 is connected to the positive terminal of battery I. The output circuit of tube 3 may be traced from the positive terminal of battery I, through primary 5 of transformer 4, plate to cathode of tube 3, to the ground terminal 2 of battery I.

One terminal of secondary 6 of this transformer is connected to ground 2. The other terminal is connected through the plate cathode path of grid controlled vacuum tube 1, and resistance 9 in parallel with condenser 8 to ground. The cathode of is connected through resistance H] to the grid of vacuum tube voltmeter ll of the cathode follower type. The output circuit of tube H can be traced from the positive terminal of battery I, plate to cathode of tube voltmeter |2, to ground 2. A clearing circuit is connected across condenser 8, comprising primary M of transformer I3, anode to cathode of grid controlled gas discharge device |6, the cathode of device l6 being connected to ground 2. A C battery ll determines the anode voltage at which device I6 breaks down, and discharges condenser 8.

Also across the secondary 6 is connected the anode and cathode of a second grid controlled vacuum tube 20, and resistance 40 in parallel with condenser 2 I. The cathode of vacuum tube is connected through resistance 23' to the grid of vacuum tube voltmeter 22 of the cathode follower type. The output circuit of tube 22 can be traced from the positive terminal of battery I, plate to cathode of tube 22, voltmeter 24, to ground 2. One terminal of the secondary l5 of transformer |3 is connected through resistance H! in parallel with condenser l8, to a rectifier auxiliary anode and cathode of tube 20, and through resistance 4|! in parallel with condenser 2| to ground 2. The control grid of vacuum tube '20 is connected through resistance 25 to line 29.

The control grid of tube 1 is connected through resistance 26 to the plate of vacuum tube 4|. The output circuit of tube 4| can be traced from the positive terminal of battery I, through resistance 21, plate to cathode of tube 4|, to the ground terminal of battery Line is connected to ground 2 and resistance 42 is connected across lines 29 and 30 to maintain line 29 at ground potential when no signal is being received.

A source of high voltage such as I, is subject to considerable undesirable voltage variations. Especially is this the case if it is obtained from rectifying an alternating current, where as stated above the voltage regulation may be as bad as forty percent. Such deleterious voltage variations would make conventional signal duration indicating devices, or electronic counters supplied from said source inoperable. I compensate for such deleterious variations in battery I by using a transformer 4, the core 43 of which saturates even on the lowest voltage'of battery As a further compensation for deleterious voltage variations of battery I, I use a high A. C. impedance screen grid tube 3 in series with primary 5. By permitting the core '43 to saturate during the period of time that tube 3 is conductive to plate current, a definite amount of energy is stored in core 43, and this definite amount of energy is not affected by voltage variations in battery by cating device is as follows.

reason of the fact that it is substantially saturated even when battery is at its lowest value. When a negative potential is instantaneously applied to the grid of tube 3, this definite amount of energy is transferred to condenser 8 by the secondary B through rectifier I. It is evident therefore that in my electronic counter a definite number of coulombs of electricity is stored in condenser 8, if tube '1 is conductive each time the grid of tube 3 causes the impedance of tube 3 to assume a negative current cut-ofi value, and that, due to the phenomena of saturation of core 43, and the high A. C. plate impedance of tube 3, this number of coulombs does not vary appreciable with voltage variations of battery I.

The detailed operation of my duration indi- Generator 3| produces alternating current at a constant predetermined frequency, the voltage of which may be several hundred volts. Vacuum tube 35. is conductive to plate current for two brief instants during each cycle of this alternating current, namely, when it is substantially zero. The high resistances 33 and 34 prevent either the first or the fourth grids of tube 35 from assuming a high positive potential. These brief surges of current through resistance 33 and the plate impedance of tube 35, cause the plate of tube 35 to go negative for brief instants such as shown between 1|, l2 and i3, 14 of graphlS of Fig. 2. These negative voltages are impressed on the control grid of tube 3 through condenser 31 and resistance 38, causing the plate impedance of tube 3 to assume an infinite value for brief instants. The magnetic energy in the core of transformer 4 collapses each time its primary circuit is rendered an open circuit by said infinite impedance of tube 3, causing a high voltage to be built up across secondary 6. If a negative impulse as shown between II, 12, graph 10 of Fig. 2, is impressed on line 29, the plate of tube 4| assumes a high positive potential and this high positive potential is impressed on the grid of rectifier I through high resistance 26. The surges across the secondary 6 then pass from the plate III to cathode of vacuum tube 1 and charge condenser 8 by an increment each time the magnetic energy of core 43 collapses. Resistance 9 is of very high value and consequently the charge on condenser 8 is retained an appreciable length of time. The grid of tube 1 remains at a positive potential for the entire time between times H and 12 of Fig. 2, thereby permitting condenser 8 to be charged by increments from secondary 6 during this entire time.

- If a positive impulse is impressed on line 29, as

shown between time 13, 14 graph 19 of Fig. 2, the plate of tube 4| is substantially at ground potential, and the plate impedance of rectifier I is substantially infinite. This positive impulse is impressed 0n the grid of vacuum tube 20 through resistance .25. The plate impedance of vacuum tube 20 becomes low, permitting the positive pulses across secondary 6 to charge condenser 2| by increments each time the magnetic field of core 43 collapses from time 13 to I4 of Fig. 2. The charges remaining on condensers 8, 2| can be read on voltmeters I2, 24, respectively. Since condenser 8 has received charges resulting from three collapses of the magnetic field of core 43, voltmeter |2 reads three. Since condenser 2| has received five charges voltmeter 24 reads five. Condenser 8 indicates the units and condenser 2| the tens therefore the number 53 has been transmitted over lines 29, 30.

After the unit condenser 8 receives a charge c m-e11 ci izen-increments; gasdischarge devised e blffiflks down; discharging oondensen a: Resistance. 19; condenser l8have= been chosenr-of'; such values that the increment impressedronrcondenser: 2| by secondary I5i wlrienrthe=brealszdownoccurs ina- GI'BSfSGSLthBIGSldiHE on voltmeter bylone number.

lm'ien'. no signal has been: received? for; some timeandthegridsofi both tubes :1: andzzflsarezat ground: potential; the secondary 6 maintains; a no signal voltage acrosscondensers wand 2 3 the magnitude or: which voltage depends on the amplification-factor:oftubes 'IpandZIL By selecting tubes" with; the proper amplification: factor and shunting-"a; voltage regulator; here shown as 1 a: gas discharge device fl acrosstsecondaryr 85, Wis possible to make thismo-signalz voltage the sameas the voltage to whichlthe clearing circuit discharges condenser. 8: For" example, thebreak down voltage of device tl' may be 455 volts, the amplification; factor. :of tube= l may: be 30. Then the nosignalt voltageacross condenser Bis15 volts; sincetube 1? would be ioiased pastM'tS- c111 rent cutoff atr minus: 15-"- volts Withi 450 vol-ts: on its plate. When the sumwoi "thevoltage across condenser 1% and thee plate imped'ance of tube l exceeds: 465' volts:v device M breaks: down and short: circuits the pulse across secondary B -to ground 24 Gas= discharge device 16" maybe-so chosenthat condensen 8 discharges to-15 volts when condenser & clearsas above" described; 7 Ihe-incrementalacharges: received by condensels 8 and 21' resulting from the= collapse of field in core-43 are-offbrief durationz- Iti-s possible however; that the beginning or the wand of an; impulse 1 may occur during this: collapses In order to'prevent false readings. I have chosen inrpulses differing: in duration; suifi'c'ientlyto make such. possible error negligibles- Inother words the duration between collapses of "the field in core 43 is small -mmpared with the-differences in length zof durations of impulses to' be measured;-

Fig. 3*. shows-amodifieation of-Fig: 1'; wherein vacuum= tubes or the screen grid type are used as rectifiers: and screen i grid" vacuum tubes are also :used'; inetlievaaeuum tube voltmetercircuits; The circuit shown in'F-i'g. 3 has= advent-ages over Fig. llin that the cathodesof all the tubes-i except the clearing gas discharge'device 169" areat ground-potential; Also-the A. C. impedances of the screen grid tubes tend, to compensate for undesirable variations in i3 supply. The principal disadvantage oi: the circuits-shown in Fig. 3 over that shown in Fig l-lisqthat therground' terminal 52 of battery, l.isi.no.t. atthe negative terminal of that battery thereby causing some undesirable coupling effects not presentinl igi 1. In1desenibing1 ig- .3 component par-tact the circuit": performing identioaltfunctions assigned-the samereferencenumerel asiinflig :1.

Ref'en-ingr=-to. Fig wa .sourcerofjnegative pulses tombe 'countedis impressed across resistance- 38.

and; through resistance. 3.8- onto the-grid of vacuum tube 3, These negative pulses block current through primary 5, and as core 43 001- lapses, a voltage is produced across secondary 6. Thus far the functioning of Figs. 1 and 3 are identical.

Across secondary 5 is connected condenser 8 in parallel with resistance 9, and rectifier 55 here shown as a screen grid vacuum tube. The screen grid of tube 56 is connected to the positive terminal of battery I. Its cathode is connected to ground 52. To measure the voltage across condenser 8 a screen grid vacuum tube voltmeter 53 is connected. The output circuit of tube 53.

'isconnected to line 29'.-

canlbeztraced fromtthmpositive; terminal of hate tery I, through voltmeter 54-;;,to::theranode and cathode; of tube'53; andtogthe groundlterminal ofzbatteryi I; Theclearing circuit: off condenser 8;: includes ground 5 52,, the; primary i I, .the anode and cathode of gas dischargedeviceslfit. Biasing battery I! has been connectedlim the grid circult: of thisadevice, to render. it conductive. only at azdesired plate voltage; I

Line :29 is connected to the .grid oivacuum tube 4|,through resistance; 2.8;- The output circuitrof tube 4 I includes the positive terminal v of: battery I resistance 27, anode and cathode 0ftube='4-i;

and-the ground terminal ofbattery' I; The anode; of:v tube 4 i' istconnected: through: voltage. divider; 5i] to'-the-negative terminal of; battery 15 The controligridiof tube"EMS-:connectedfthliough resistance: 26 to an intermediate point on divider 6B).

Transformer 4 has an auxiliary-secondary 58'; Across secondary 53' is. connectedvcondenser'flii inparallel; with resistance 45; and screen grid vacuum tube rectifier 5.1. The screen gridfof tube 5'! isconnected to the positive 5 terminal" of: bathtery I. Its cathode is connected to ground SZ' "Vacuum tube voltmeter comprising screen' gri'd tube 55 and voltmeter 56 is connectedto-meas ure the-voltage across condenser 212* Secondary i 5 is I connected through condenser Win-parallel with resistance i9' sto an auxiliary anodein tube 51: The control grid of tube 51 is' connected through resistance 25 to a nud pointomvoltage divider 6i of highohmic value. One terminal of: this voltage divider is connected'it'o the negativesterminal of battery-I, and the other terminal A voltagelimiter com-- prising gas discharge device 44* isconnected across the secondary-53L In ope-ration" when the field of core= 46" collapses high voltage is set up across -secondanies: 5' audits; If a negativeimpulseis-being impressed ending-29'.- the plate of tube tilassumesa positive potential: and a positive potential is impressed on the control gridof 1 tube 55 permitting current to flow fi om -the=lower terminal of secondary e; anode to cathode of tube 1 5 3, 7 through 1 condenser 8' to the 1 upper terminal of secondary- 5 charging the lower plate of condenser positive: Condenser 8 continues to be; charged by an increment each time the cores fi collapsesas long as tube 56 is-conductiv e If apositive-impulse is impressed online 29 3 the -control grid of tu be-5"i is positive; andicurrent fiows from thelower'terminal of secondary 58 through the plate impedance of tube -'5'i--an-d condenser 21130 the upper terminal oi-secondary 58; charging condenser '2 May an I increment each tame-corset? collapses; The C; time eiement of resistance -i 9-} condenser" Hl'has been'so chosen as to impress an incremental charge on: condenser 2! each' time. condenser "8"clears through primary M" and gas dischargedevice i5; Cone denser "8' is in the input'circuit of'tuhe 53$ Condenser Zl is in the input circuit of tube 55. Tubes 53, 55 being of the screen grid type have a high A. 0. plate impedance, and consequently the current through voltmeters 54, 56 is not appreciably afiected by large deleterious variations in B voltage of battery I.

If no signal is received over line 29, the control grids of both tubes 55, 51 are biased past the current cutoff and a very high voltage tends to build up across secondaries 6, 58. To prevent damage to circuit elements, gas discharge device 44 has been shunted across secondary 58 as a protective device.

It is obvious that my invention may take widely different forms from these illustrated, and it is to be limited in scope only as defined in the following claims.

What I claim is:

1. An electronic counter comprising: a transformer having a primary, a secondary and a core, a Vacuum tube having a plate, cathode and grid, a source of voltage, means for connecting said source of voltage, said primary, said plate, and said cathode in series, a rectifier, an accumulator condenser, means for connecting said secondary, said rectifier, and said condenser in series, means for maintaining said grid at a sufficiently positive potential to cause the current in said primary to saturate said core, means for impressing a negative potential on said grid to cause substantially all the energy stored in said core to be dissipated in current flow in the circuit of said secondary, and impress an incremental charge on said condenser, said last means comprising an electronic switch controlled by a source of predetermined frequency, and means for indicating the charge 01 said condenser.

2. In-an impulse polarity and duration indi cating device, the secondary of a transformer, means for varying the energy content of the total current flowing in said secondary in accordance with the duration of an impulse to be measured, a plurality of condensers, means for charging any selected one of said condensers with said current dependin on the polarity of said impulse, and means for indicating the charges on said condensers.

3. In an impulse duration indicating device, means for producing, at a predetermined frequency, increments of electrical current having substantially equal energy content for the duration of an impulse to be measured, a plurality of accumulator condensers, means responsive to the direction of voltage change of said impulse for applying said increments to any selected one of said condensers for said duration, and means for indicating the voltage of the charge on each of said condensers.

4. In an electronic counter, means for producing increments of electrical current havin substantially equal energy content, a plurality of accumulator condensers, means for receiving input pulses, a device having a plurality of units, each unit being conductive at a different polarity of voltage of said pulses, a, plurality of parallel circuits connected across said increment producin means, each of said circuits comprising a separate one of said units and a separate one of said condensers, and means for indicating the charges on said condensers.

5. An impulse duration responsive device, comprising: a plurality of accumulator condensers, a transformer having a primary, a seconclary, and a core, means for passing a current through said primary to saturate said core, means for interrupting said current at a predetermined frequency throughout the duration of an impulse to produce increments of electrical current in said secondary ,of substantially equal energy content, means for charging any one of said condensers with said increments depending on the polarity of said impulse, and means for indicating the charge on said condensers.

6. An impulse duration indicating device, comprising: a plurality of accumulator condensers, a transformer having a primary, a secondary and a core, a source of current, a vacuum tube having an input and an output circuit, means for connecting said source, and said primary in said output circuit, means for impressing a positive voltage on said input circuit to produce a current flow in said output circuit to saturate said core, a selector having a plurality of vacuum tubes, the plate impedance of each of said last tubes being small depending on the direction of vcltagechange of an impulse, a plurality of circuits connected across said secondary, each of said last circuits including a, separate one of said condensers and the plate impedance of a separate one of said last tubes, means for impressing negative blocking potentials at a predetermined frequency on said input circuit to impress incremental charges on a selected one of said condensers depending on said direction of change of said impulse, and means for indi cating the charges on said condensers.

7. An impulse duration indicating device comprising: a transformer having a core, a primary, and a plurality of secondaries, means for passing a current through said primary to saturate said core, a selector, having units each conductive at difierent polarities of an'impulse to be measured, a plurality of accumulator condensers, means for electrically connecting a separate one of said units and a separate one of said condensers across each of said secondaries, means for interrupting the current in said primary at a predetermined frequency to charge a selected one of said condensers depending on the polarity of said impulse, and means for indicating the charge on said condensers.

' OLIVER T. FRANCIS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,755,060 Gay Apr. 15, 1930 1,933,976 Hanson Nov. '7, 1933 2,110,015 Fitzgerald Mar. 1, 1938 2,272,998 Bjornson Feb. 10, 1942 2,284,101 Robins May 26, 1942 2,332,300 Cook Oct. 19, 1943 

